Journal of China University of Geosciences最新文献

{"title":"Subdivision of Permian Fossil Communities and Habitat Types in Northeast Sichuan, South China","authors":"Yan Jiaxin ,&nbsp;Ma Zhixin ,&nbsp;Xie Xinong ,&nbsp;Xue Wuqiang ,&nbsp;Li Bo ,&nbsp;Liu Dongqin","doi":"10.1016/S1002-0705(08)60049-7","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60049-7","url":null,"abstract":"<div><p>Recent achievement in hydrocarbon exploration in Northeast Sichuan demonstrated that Permian calcareous and argillaceous deposits are the major contributing source rocks. Reevaluation on the hydrocarbon potential of the Permian strata over the whole Yangtze region is thus to be desired. A comprehensive corroboration was carried out at the Shangsi Section, Guangyuan, Northeast Sichuan, which is believed to be another promising area in South China. This article deals with the ecological and depositional conditions of the Permian strata in the section, including the Chihsia, Maokou, Wujiaping, and Dalong formations, which share some similarities with those occurring in the broad Yangtze carbonate platforms. Five fossil communities of <em>Mizzia-Permocalculus, Hayasakaia, Inozoan</em>, Ostracod, and Crinoid were identified in the Yangtze region and described in detail including their components and occurrence. On the basis of the fossil communities and depositional features, 23 habitat types, mainly occurring from inner to outer shelves, were recognized at the Shangsi Section in order to reconstruct the depositional conditions and accordingly to evaluate the paleoproductivity. In addition, the subdivision of Chihsia Formation in the section was revised, which would be of significance for the reconstruction of the Chihsian paleogeography in the study area.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 5","pages":"Pages 441-450"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60049-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72246134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Occurrence of Organic Matter in Calcimicrobialites across Permian–Triassic Boundary in Huayingshan Region, Sichuan, South China","authors":"Yang Hao ,&nbsp;Wang Yongbiao ,&nbsp;Chen Lin","doi":"10.1016/S1002-0705(08)60057-6","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60057-6","url":null,"abstract":"<div><p>Calcimicrobialites across the Permian-Triassic boundary in Huayingshan region were investigated using the fluorescence microscopic measurements to understand the occurrence of organic matter. The microbialites are composed of micrite matrix and coarse spar cement. Abundant rhombic or magnetic needle-like carbonate minerals were observed adrift within the cement. The fluorescence microscopic measurement indicates the micrite matrix in microbialites shows the most abundant organic matter, with the rhombic or magnetic needle-like carbonate minerals and coarse spar cement coming to the 2nd and the 3rd, respectively. Organic matter is mainly preserved in the space between the grains of the micrite minerals but almost evenly distributed in the rhombic or magnetic needle-like carbonate minerals. As one of the common diagenesis types, dolomitization is observed to occur in the microbialites in Huayingshan. However, the carbonate cement in microbialites still has high content of element Sr as shown by the microprobe analysis, reflecting that the dolomitization might have happened in a restricted environment. Observation under the fluorescence microscope shows that dolomitization just led to the redistribution of organic matter in the grain space of dolomite minerals, inferring that the diagenesis has a slight effect on the preservation, and thus on the content of organic matter in the microbialites.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 5","pages":"Pages 518-525"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60057-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72246130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Subdivision of Permian Fossil Communities and Habitat Types in Northeast Sichuan, South China","authors":"Yang Jiaxin, Mao Zhixin, Xie Xinong, Xue Wuqiang, Li Bo, Li Dongqin","doi":"10.1016/S1002-0705(08)60049-7","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60049-7","url":null,"abstract":"","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"32 1","pages":"441-450"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84896224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial Mats in the Mesoproterozoic Carbonates of the North China Platform and Their Potential for Hydrocarbon Generation","authors":"Shi Xiaoying ,&nbsp;Zhang Chuanheng ,&nbsp;Jiang Ganqing,&nbsp;Liu Juan ,&nbsp;Wang Yi ,&nbsp;Liu Dianbo","doi":"10.1016/S1002-0705(08)60060-6","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60060-6","url":null,"abstract":"<div><p>The well-preserved Mesoproterozoic succession in the North China platform consists mainly of three lithological associations including peritidal quartz sandstone, shallow marine and lagoonal dark to black shales, and shallow epeiric carbonates, with a total thickness of up to 8 000 m. In addition to well-documented microplants, macroalgae, and microbial buildups, abundant microbially induced sedimentary structures (MISS) and mat-related sediments have been recognized in these rocks. Intensive microbial mat layers and MISS are especially well preserved in the carbonates of the upper Gaoyuzhuang (ca. 1.5 Ga) and lower Wumishan (ca. 1.45 Ga) formations, indicating diversified microbial activities and a high organic production. In these petrified biomats, putative microbial fossils (both coccoidal and filamentous) and framboidal pyrites have been identified. The abundance of authigenic carbonate minerals in the host rocks, such as, acicular aragonites, rosette barites, radial siderites, ankerites, and botryoidal carbonate cements, suggests authigenic carbonate precipitation from anaerobic oxidation of methane (AOM) under anoxic/euxinic conditions. Warm climate and anoxic/euxinic conditions in the Mesoproterozoic oceans may have facilitated high microbial productivity and organic burial in sediments. Although authigenic carbonate cements may record carbonate precipitation from anaerobic methane oxidation, gas blister (or dome) structures may indicate gas release from active methanogenesis during shallow burial. Bituminous fragments in mat-related carbonates also provide evidence for hydrocarbon generation. Under proper conditions, the Mesoproterozoic mat-rich carbonates will have the potential for hydrocarbon generation and serve as source rocks. On the basis of petrified biomats, a rough estimation suggests that the Mesoproterozoic carbonates of the North China platform might have a hydrocarbon production potential in the order of 10 × 10⁸ t.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 5","pages":"Pages 549-566"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60060-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72246059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Main Controlling Factors of Organic Matter Richness in a Permian Section of Guangyuan, Northeast Sichuan","authors":"Xie Xinong ,&nbsp;Li Hongjing ,&nbsp;Xiong Xiang ,&nbsp;Huang Junhua ,&nbsp;Yan Jiaxin ,&nbsp;Qin Jianzhong ,&nbsp;Tenger ,&nbsp;Li Wu","doi":"10.1016/S1002-0705(08)60056-4","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60056-4","url":null,"abstract":"<div><p>A complete Permian section in Guangyuan, Northeast Sichuan, has been investigated, to explore the variation in organic matter richness and its main controlling factors. The research results of the detailed lithological description and organic/inorganic geochemical analysis of about 325 samples indicate that a high content of total organic carbon (TOC) occurs in calcareous mudstones and laminated marls or thin-bedded limestones. In carbonate rocks, the TOC content is negatively related to the thickness of the massive beds; the thinner the bed is, the higher the TOC content is. Marine organic matter is enriched in the outer shelf and relatively shallow basin floor environments with the maximum TOC contents of 5.07% and 14.6%, respectively. The main factors that affect the quantity and quality of marine organic matter include primary productivity, depositional processes, and redox conditions during deposition and the early diagenesis stage. Three intervals of marine good quality source rocks are identified in this section; they are lower Chihsia Formation, topmost Maokou Formation, and the middle segment of the Dalong Formation. They are formed in anoxic environments, in association with high primary productivity. Among these, high productivity in the lower Chihsia interval may originate from an upwelling flow area, whereas, in the rest of the intervals, it is inferred to be related to hot fluid activity due to volcanic eruption. The results of this study suggest that good quality marine source rocks in the Permian strata offer significant hydrocarbon potential.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 5","pages":"Pages 507-517"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60056-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72246121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Evidence for Primary Producers and Paleo-environmental Conditions in Mesoproterozoic in the Xuanlong Depression in North China","authors":"Luo Genming ,&nbsp;Xie Shucheng ,&nbsp;Wu Wenjun ,&nbsp;Sun Si ,&nbsp;Huang Junhua ,&nbsp;Shi Xiaoying","doi":"10.1016/S1002-0705(08)60061-8","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60061-8","url":null,"abstract":"<div><p>The molecular organic compounds have been identified by gas chromatography (GC) and GC-mass spectrometry (GC-MS) from Mesoproterozoic rocks in the Xuanlong depression in North China. The main saturated compounds are <em>n</em>-alkanes, monomethylalkanes, <em>n</em>-alkylcyclohexanes, acyclic isoprenoids, and hopanes. The dominant lower-molecular-weight <em>n</em>-alkanes are indicative of the main contribution of microorganisms, in particular, the chemosynthetic bacteria. The presence of abundant monomethylalkanes (mid- and end-branched) and the long chained (&gt;C₂₀) acyclic isoprenoids indicates the existence of abundant bacteria and/or archaea in ancient oceans. The low abundance of pristane and phytane is suggestive of the relatively low abundance of photosynthetic autotrophs in comparison with chemosynthetic bacteria in the Mesoproterozoic oceans in North China. The sedimentary environmental condition is suboxic/anoxic, as indicated by the low value of the Pr/Ph ratio as well as the presence of abundant sulfur-bearing organic compounds, consistent with the other geochemical data in North China and elsewhere in the world. Both the composition of the primary producers and the sedimentary environmental conditions are favorable for the formation of hydrocarbon source rocks.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 5","pages":"Pages 567-576"},"PeriodicalIF":0.0,"publicationDate":"2008-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60061-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72246135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extraction of Mineral Alteration Zone from ETM+ Data in Northwestern Yunnan, China","authors":"Zhao Zhifang ,&nbsp;Zhang Yujun ,&nbsp;Cheng Qiuming ,&nbsp;Chen Jianping","doi":"10.1016/S1002-0705(08)60075-8","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60075-8","url":null,"abstract":"<div><p>Alteration is regarded as significant information for mineral exploration. In this study, ETM+ remote sensing data are used for recognizing and extracting alteration zones in northwestern Yunnan, China. The principal component analysis (PCA) of ETM+ bands 1, 4, 5, and 7 was employed for OH⁻ alteration extractions. The PCA of ETM+ bands 1, 3, 4, and 5 was used for extracting Fe²⁺ (Fe³⁺) alterations. Interfering factors, such as vegetation, snow, and shadows, were masked. Alteration components were defined in the principal components (PCs) by the contributions of their diagnostic spectral bands. The zones of alteration identified from remote sensing were analyzed in detail along with geological surveys and field verification. The results show that the OH⁻ alteration is a main indicator of K-feldspar, phyllic, and prophilized alterations. These alterations are closely related to porphyry copper deposits. The Fe²⁺ (Fe³⁺) alteration indicates pyritization, which is mainly related to hydrothermal or skarn type polymetallic deposits.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 4","pages":"Pages 416-420"},"PeriodicalIF":0.0,"publicationDate":"2008-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60075-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72286041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Prediction for Deep Mineral Exploration","authors":"Zhao Pengda ,&nbsp;Cheng Qiuming ,&nbsp;Xia Qinglin","doi":"10.1016/S1002-0705(08)60063-1","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60063-1","url":null,"abstract":"<div><p>On reviewing the characteristics of deep mineral exploration, this article elaborates on the necessity of employing quantitative prediction to reduce uncertainty. This is caused by complexity of mineral deposit formational environments and mineralization systems as increase of exploration depth and incompleteness of geo-information from limited direct observation. The authors wish to share the idea of “seeking difference” principle in addition to the “similar analogy” principle in deep mineral exploration, especially the focus is on the new ores in depth either in an area with discovered shallow mineral deposits or in new areas where there are no sufficient mineral deposit models to be compared. An on-going research project, involving Sn and Cu mineral deposit quantitative prediction in the Gejiu area of Yunnan Province, China, was briefly introduced to demonstrate how the “three-component” (geoanomaly-mineralization diversity-mineral deposit spectrum) theory and non-linear methods series in conjunction with advanced GIS technology, can be applied in multi-scale and multi-task deep mineral prospecting and quantitative mineral resource assessment.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 4","pages":"Pages 309-318"},"PeriodicalIF":0.0,"publicationDate":"2008-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60063-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72286043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Special Issue of Mathematical Geosciences for the 33rd IGC","authors":"Cheng Qiuming","doi":"10.1016/S1002-0705(08)60062-X","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60062-X","url":null,"abstract":"","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"320 1","pages":"307-308"},"PeriodicalIF":0.0,"publicationDate":"2008-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76283294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Grey Fuzzy Comprehensive Model for Evaluation of Geological Structure Complexity","authors":"Zhou Yunxia ,&nbsp;Zhou Yongzhang ,&nbsp;Xie Shuyun ,&nbsp;Cao Daiyong ,&nbsp;Qiu Xiangrong","doi":"10.1016/S1002-0705(08)60078-3","DOIUrl":"https://doi.org/10.1016/S1002-0705(08)60078-3","url":null,"abstract":"<div><p>Several structure sets (faults and folds) are characterized by their self-similarity properties. Herein, we discuss the degrees of complexity of fractures by introducing the box-counting fractal dimension of faults as a key criterion to be used in comprehensive fuzzy analysis model for evaluation of the complexity of structures. Totally, eight criteria including density, intensity, length of faults, types and box-counting fractal dimension of faults, the intersection angle between faults and coal beds, gradient coefficients, dip angles of the coal beds, and variation coefficients of dip angles of the coal seams, were used for the evaluation purpose. The grey fuzzy comprehensive assessment model was used to rank the relative importance of these criteria. Scores indicating the complexity of structure were calculated on the base of criteria values and their weights for each sub-area of the study area in the Pansan coal mine district in the southern Anhui Province, China. The result on the calculated complexity of structure is useful for mining planning in the study area.</p></div>","PeriodicalId":100762,"journal":{"name":"Journal of China University of Geosciences","volume":"19 4","pages":"Pages 436-440"},"PeriodicalIF":0.0,"publicationDate":"2008-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1002-0705(08)60078-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72286032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}